Treatment of super heavy oil wastewater by a combined process of lignite‐activated coke adsorption and immobilized biological filter degradation: performance and the relevant microbial community analysis

Abstract

AbstractBACKGROUNDTreatment of super heavy oil wastewater (SHOW) is an increasing problem due to the large amounts of recalcitrant contaminants. Thus advanced techniques should be explored.RESULTSA pilot field study was conducted by unsaturated ligntie‐activated coke (LAC) pre‐adsorption–immobilized biological filter (I‐BF) degradation–LAC post‐adsorption. Specially, the unsaturated LAC from the post‐adsorption stage was sent to the influent wastewater for pre‐adsorption. Through this novel process, the effluent can meet the prescribed discharge standard, and LAC dosage was significantly lower compared with the process without pre‐adsorption. Gas chromatography‐mass spectrometry (GC‐MS) demonstrated that pre‐adsorption could remove mostly organic substances which benefits the subsequent bio‐treatment; in particular, I‐BFs could remove phenols, organic acid compounds and light alkanes, whereas post‐adsorption preferentially removed amide. Liquid chromatography with organic carbon detection (LC‐OCD) indicated that pre‐adsorption could easily remove hydrophobic organic carbon (HOC), whereas I‐BFs and post‐adsorption principally removed neutrals. Thus, this process readily removes HOC, organic acids, biopolymers and neutrals, although humics (proven to be sewage fulvic acids) and building blocks are hard to remove. We also monitored the microbial community based on polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) and revealed that the predominant bacteria in the I‐BF reactors were Bacteroides spp., Pseudomonas spp., Thermomonas spp., Sphingomonadaceae spp., Sphingomonas spp. and Rhizobium spp.CONCLUSIONThis process provides an effective way for the treatment of SHOW. Results concerning the removal mechanism of recalcitrant contaminants and the in‐depth study of predominant bacteria may provide significant guidance for other wastewater treatments. © 2018 Society of Chemical Industry